xapian-core/include/xapian/termiterator.h

   1 /** @file
   2  *  @brief Class for iterating over a list of terms
   3  */
   4 /* Copyright (C) 2007,2008,2009,2010,2011,2012,2013,2014,2015 Olly Betts
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License as
   8  * published by the Free Software Foundation; either version 2 of the
   9  * License, or (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301
  19  * USA
  20  */
  21
  22 #ifndef XAPIAN_INCLUDED_TERMITERATOR_H
  23 #define XAPIAN_INCLUDED_TERMITERATOR_H
  24
  25 #if !defined XAPIAN_IN_XAPIAN_H && !defined XAPIAN_LIB_BUILD
  26 # error Never use <xapian/termiterator.h> directly; include <xapian.h> instead.
  27 #endif
  28
  29 #include <iterator>
  30 #include <string>
  31
  32 #include <xapian/attributes.h>
  33 #include <xapian/derefwrapper.h>
  34 #include <xapian/positioniterator.h>
  35 #include <xapian/types.h>
  36 #include <xapian/visibility.h>
  37
  38 namespace Xapian {
  39
  40 /// Class for iterating over a list of terms.
  41 class XAPIAN_VISIBILITY_DEFAULT TermIterator {
  42   public:
  43     /// Class representing the TermIterator internals.
  44     class Internal;
  45     /// @private @internal Reference counted internals.
  46     Internal * internal;
  47
  48     /// @private @internal Construct given internals.
  49     explicit TermIterator(Internal *internal_);
  50
  51     /// Copy constructor.
  52     TermIterator(const TermIterator & o);
  53
  54     /// Assignment.
  55     TermIterator & operator=(const TermIterator & o);
  56
  57 #ifdef XAPIAN_MOVE_SEMANTICS
  58     /// Move constructor.
  59     TermIterator(TermIterator && o)
  60         : internal(o.internal) {
  61         o.internal = nullptr;
  62     }
  63
  64     /// Move assignment operator.
  65     TermIterator & operator=(TermIterator && o) {
  66         if (this != &o) {
  67             if (internal) decref();
  68             internal = o.internal;
  69             o.internal = nullptr;
  70         }
  71         return *this;
  72     }
  73 #endif
  74
  75     /** Default constructor.
  76      *
  77      *  Creates an uninitialised iterator, which can't be used before being
  78      *  assigned to, but is sometimes syntactically convenient.
  79      */
  80     XAPIAN_NOTHROW(TermIterator())
  81         : internal(0) { }
  82
  83     /// Destructor.
  84     ~TermIterator() {
  85         if (internal) decref();
  86     }
  87
  88     /// Return the term at the current position.
  89     std::string operator*() const;
  90
  91     /// Return the wdf for the term at the current position.
  92     Xapian::termcount get_wdf() const;
  93
  94     /// Return the term frequency for the term at the current position.
  95     Xapian::doccount get_termfreq() const;
  96
  97     /// Return the length of the position list for the current position.
  98     Xapian::termcount positionlist_count() const;
  99
 100     /// Return a PositionIterator for the current term.
 101     PositionIterator positionlist_begin() const;
 102
 103     /// Return an end PositionIterator for the current term.
 104     PositionIterator XAPIAN_NOTHROW(positionlist_end() const) {
 105         return PositionIterator();
 106     }
 107
 108     /// Advance the iterator to the next position.
 109     TermIterator & operator++();
 110
 111     /// Advance the iterator to the next position (postfix version).
 112     DerefWrapper_<std::string> operator++(int) {
 113         const std::string & term(**this);
 114         operator++();
 115         return DerefWrapper_<std::string>(term);
 116     }
 117
 118     /** Advance the iterator to term @a term.
 119      *
 120      *  If the iteration is over an unsorted list of terms, then this method
 121      *  will throw Xapian::InvalidOperationError.
 122      *
 123      *  @param term     The term to advance to.  If this term isn't in
 124      *                  the stream being iterated, then the iterator is moved
 125      *                  to the next term after it which is.
 126      */
 127     void skip_to(const std::string &term);
 128
 129     /// Return a string describing this object.
 130     std::string get_description() const;
 131
 132     /** @private @internal TermIterator is what the C++ STL calls an
 133      *  input_iterator.
 134      *
 135      *  The following typedefs allow std::iterator_traits<> to work so that
 136      *  this iterator can be used with the STL.
 137      *
 138      *  These are deliberately hidden from the Doxygen-generated docs, as the
 139      *  machinery here isn't interesting to API users.  They just need to know
 140      *  that Xapian iterator classes are compatible with the STL.
 141      */
 142     // @{
 143     /// @private
 144     typedef std::input_iterator_tag iterator_category;
 145     /// @private
 146     typedef std::string value_type;
 147     /// @private
 148     typedef Xapian::termcount_diff difference_type;
 149     /// @private
 150     typedef std::string * pointer;
 151     /// @private
 152     typedef std::string & reference;
 153     // @}
 154
 155   private:
 156     void decref();
 157
 158     void post_advance(Internal * res);
 159 };
 160
 161 bool
 162 XAPIAN_NOTHROW(operator==(const TermIterator &a, const TermIterator &b));
 163
 164 /// Equality test for TermIterator objects.
 165 inline bool
 166 operator==(const TermIterator &a, const TermIterator &b) XAPIAN_NOEXCEPT
 167 {
 168     // Use a pointer comparison - this ensures both that (a == a) and correct
 169     // handling of end iterators (which we ensure have NULL internals).
 170     return a.internal == b.internal;
 171 }
 172
 173 bool
 174 XAPIAN_NOTHROW(operator!=(const TermIterator &a, const TermIterator &b));
 175
 176 /// Inequality test for TermIterator objects.
 177 inline bool
 178 operator!=(const TermIterator &a, const TermIterator &b) XAPIAN_NOEXCEPT
 179 {
 180     return !(a == b);
 181 }
 182
 183 }
 184
 185 #endif // XAPIAN_INCLUDED_TERMITERATOR_H